1. Field of the Invention
The present invention relates to polyvinyl chloride (PVC) compositions and methods of manufacture and their use in cables, specifically, cables carrying for carrying electric currents, and most specifically, computer cables.
2. Description of the Prior Art
Known electrical cables contain at least one electrically conductive wire and an outer insulator or jacket. Typically for computer cables, there are a plurality of individually insulated conductive wires, which are typically copper and the outer insulation is often a rubber or plastic material, often PVC based. The wires typically correspond to the various xe2x80x9cpinsxe2x80x9d used in a computer connection and are individually held in a connector for easy connection to the appropriate computer or peripheral. The individual wire insulation is often color coded for ease of following the connections through the cable. In addition, in this type of cable, a sheath, at least partially metal, is often disposed around the plurality of wires. The sheath is typically an aluminum/Mylar layer covered by a copper/tin braid. The sheath can serve different purposes, but can be often utilized as a common ground connection, or as a shield against RF (radio frequency) interference. In various applications, other layers, i.e. additional insulators, may be added as necessary.
Computer cables typically provide a monochromatic exterior appearance, often in black, grey or beige. This appearance is typically provided by having an opaque outer insulator about the cable in the desired color. It is also common practice in the field to color coordinate the connectors of the computer cables, to simplify the correct installation of the cables by the end user. When using a transparent or translucent outer insulation, the appearance of the metal sheath will likely also affect the final appearance of the cable.
The present invention is a translucent PVC material which, when plasticized, exhibits a tinted appearance. In addition, metallic appearing flecks are added to the PVC compound during manufacture, which provide an aesthetically appealing appearance. Additionally, when formed into a cable, particularly a computer cable, the appearance of the cable is affected by both the translucent PVC, and the underneath material, specifically the underlying sheath. Different numbers of conductive wires and different end connectors can be provided with the cable to make the cable of the present invention suitable for a number of different purposes.
Thus, an object of the invention is a composition for a PVC material which, when used in a cable, exhibits an aesthetically pleasing exterior appearance as described above.
A further object of the invention is a method of making a PVC composition, for the making of cables, particularly, computer cables.
An additional object of the present invention, is to produce a computer cable which is aesthetically pleasing and provides improved flame retardant properties over standard PVC compositions.
The PVC cables of the present invention present a color and appearance that is aesthetically pleasing. In particular, the cables of the present invention provide a color base, preferably gold, and also provide a metallic appearing xe2x80x9cfleckedxe2x80x9d or xe2x80x9cspeckledxe2x80x9d appearance, preferably reflective gold tinted flecks. Additionally, the gold colored PVC can have improved flame retardant properties over standard cables.
A preferred composition for the PVC outer coating or jacket of the according to the present invention includes the following materials. The preferred embodiment is based on, first, a basic thermoplastic widely used for cable insulation and jackets. A preferred starting material would be Formosa Plastics xe2x80x9cS-70xe2x80x9d which is a PVC base material. This PVC base material is especially suitable for use in the present invention. This PVC base material is used in conjunction with a plasticizer, such as xe2x80x9cR-65xe2x80x9d by the Juyee company. This plasticizer, based on triaryl phosphate, is commonly used in transparent and flame retardant cables.
In addition to the above components, an additional plasticizer, in particular DIDP, by Coin Chemical Ind. is also added. DIDP comprises isodecanol and phthalic anhydride and provides good electric insulation (resistance) and high temperature resistance. This product is widely used in high temperature cabling. As an alternative to the DIDP, DINP, a non-toxic composition of isodecanol and phthalic acid anhydride can be substituted. An oil product, preferably an epoxidized soybean oil product D-81 (Epoxy D-81), by the Juyee Co. can increase the heat retardant properties of the final PVC, and in addition, can provide a desirable color adjustment in the final PVC product. Clear PVC materials tend to not have good fire retardant properties. The color adjustment of the present invention, not only yields an aesthetically appealing gold/yellow tinted appearance, but additionally provides an improved fire resistance.
Stabilizers are also added to the mixture to produce the final PVC product. Preferred stabilizers are: JU-2114, by the Juyee Co., which is a liquid PVC stabilizer based on barium, cadmium and zinc, which positively affects the heating characteristics and has good transparency; E-190 by the Juyee Co. which is a component suitable for clear jackets and serves as a heat stabilizer, comprising a liquid high molecular weight fatty acid ester; and LC-541, also by the Juyee Co., which is also a liquid stabilizer based on cadmium, barium and zinc, which is suitable for bare copper products. In the most preferred embodiment of the present invention, all of the stabilizers are used in making the PVC product. As an alternative to the LC-541, an example of an acceptable alternative would be SU-965D. SU-965D is a stabilizer based upon Di-N-Butyl tin mercaptide.
The E-190 stabilizer can be especially beneficial in that it has a very low volatility, therefore it is a material which does not vaporize easily in the air, or especially under heat. Therefore, during the production of the PVC material it will tend to not vaporize and the heat will instead be absorbed by the PVC. Thus this compound is especially stable during the production process.
An anti-rusting (anti-oxidation) agent is also preferably used in the PVC mixture. A preferred agent is B.T. Anti-Rust agent again by the Juyee Co. This component comprises about 99% Benzotriazole coating to prevent oxidation and rust.
Finally, an additional material is added to provide the speckled appearance. In the preferred embodiment, where a gold tinted cable with gold flecking is desired, a material such as 509B powder from Red-Sun Chemical, of Osaka Japan, is preferred. This material is a foil-like reflective material which will be reflective through the tinted PVC it is to be immersed in. This material is a PET plastic material which is high temperature retardant (240 degrees C) non-toxic and resistant to acid and alkaline environments. This material provides an aesthetically pleasing appearance, and is well suited to formation of cables according to the present invention. When in the PVC, this material yields a reflective, or metallic appearing particle yielding a speckled appearance.
In at least one embodiment of the present invention, the cable can have a gold tint. In at least one preferred embodiment of the present invention, the gold tint can be provided by at least one plasticizer used in the composition for the cable.
The above materials, and the products made from the process described herein, comply with the safety standards found in UL 20276, UL 2725 and UL 2919.
It is important to note that powder stabilizers can tend to have better flame retardant properties. Because of the transparency and final appearance of the product desired herein, liquid stabilizers are preferred in the present invention. Thus, the color affecting stabilizers are used to further affect the final appearance of the product.
By weight, the PVC raw materials comprise about 57.9 weight percent PVC powder; about 5.8 weight % R-65 powder; about 32.4 weight % DIDP (or equivalent); about 2.3 weight % D-81; about 0.2 weight % E-190; about 0.2 weight % JU-2114; about 0.7 weight % SU 965D; about 0.1 weight % B.T. anti-rust; and about 0.3 weight % gold powder.
Im an especially preferred embodiment, 50 kg of S-70, 5 kg of R-65; 28 kg of DIDP, 2 kg of D-81, 0.2 kg of E-190, 0.2 kg of JU-2114, 0.5 kg of LC-541, 0.1 kg of B.T. anti-rust and 0.3 kg of 509B powder are combined to produce a PVC composition for use in a computer cable. In the preferred embodiment, tolerance of +/xe2x88x925% (by weight) of the components is generally acceptable to yield an acceptable PVC product with an acceptable tint and texture. With regard to the 509B powder, varying the amount of the powder will greatly affect the final appearance and so in order to maintain consistency of appearance, minimizing the variance of this component is especially crucial.